A light emitting device using a light emitting diode as a light emitting source is one to obtain light emission of a desired color by letting light be emitted from a light emitting diode chip and subjecting the emitted light to wavelength conversion by a phosphor.
For example, in order to obtain white light by a light emitting device, blue light is permitted to be generated by a light emitting diode chip of gallium nitride (GaN) type, and the blue light is permitted to pass through a wavelength conversion layer that holds a phosphor of yttrium•aluminum•garnet (YAG) type. Thus, light from red to green obtained as fluorescence is combined with blue color passed through the phosphor, whereby it is possible to obtain emission of white light.
The above wavelength conversion layer is such that one obtained by dispersing various phosphors to e.g. a resin component, is placed on the light emitting diode chip. Therefore, due to the heat radiation from the light emitting diode chip itself and the oxygen component in the atmosphere, deterioration of the wavelength conversion performance by long-term use is worried.
Whereas, a construction has been proposed wherein a plate-form protection member is provided which has a light transmittance with respect to light emitted from a light emitting diode chip and which is air-tightly secured to a package body in such a form to close a housing recess on one surface side of a semiconductor substrate (see Patent Document 1). According to this construction, it is possible to protect a light emitting diode chip housed inside, from mechanical destruction factors or environmental destruction factors from outside, without using a conventional sealing resin, and thus, it is possible to improve the reliability.